All you need to know about OBD | OBD 100 | 5
en
569624 Rev "A"
2013-12-19
|
Robert Bosch GmbH
4. All you need to know
about OBD
4.1
What are OBD, OBD II, OBD-2
and EOBD
OBD (on-board diagnosis) means that
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Emission-related components and systems
are monitored by the vehicle whilst driving
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Any malfunctions are recorded and indicated
by a warning lamp (MIL)
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This information can be read by a diagnostic
tester
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A further purpose of OBD is to protect
vulnerable components such as catalytic
converters.
In these operating instructions, OBD is always
used to refer to the standard OBD-2 (OBD II).
OBD-2 has been obligatory in the USA for all
new vehicles since 1st January 1996. In the EU,
OBD-2 was introduced for new vehicles with
gasoline engine in January 2001 with the EURO-
3 standard and for diesel vehicles in January
2004. EOBD is the abbreviation for European
on-board diagnosis based on OBD-2.
The OBD diagnostic system is integrated into the
electronic control unit and constantly monitors
defined emission-related components in the
vehicle. The malfunction indicator light (MIL)
informs the driver of OBD faults reported by the
electronic control unit.
A minimum of five monitoring systems are
provided:
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Emission-related components
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Missing combustion
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Fuel system
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Upstream and downstream Lambda sensors
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Catalytic converter efficiency
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Exhaust gas recirculation
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Secondary air system
The following are permanently monitored:
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Missing combustion
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Fuel system (injection times)
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Circuits for emission-related components
The following are monitored once per drive
cycle:
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Lambda sensor function
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Catalytic converter function
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Speed, temperature and Lambda sensor
values can also be read out by way of the
OBD diagnostic socket.
4.2
Is my vehicle provided with OBD
In the EU, OBD-2 was introduced for new vehicles
with gasoline engine in January 2001 with the
EURO-3 standard and for diesel vehicles in
January 2003.
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Vehicles manufactured before these dates
may however also be provided with OBD.
4.3
Where is the OBD diagnostic
socket located
The OBD diagnostic socket is usually situated
in the driver's footwell in the area of the center
console or in the glove compartment.
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The installation location can also be looked
up in the owner's manual of the vehicle
concerned or found in the internet.
4.4
Why and when does the mal-
function indicator light (MIL)
come on
The malfunction indicator light must come on
briefly when switching on the ignition. The
malfunction indicator light must go out at the
latest when the engine is started. The MIL status
(malfunction indicator light "On" or "Off") is
read from the vehicle electronic control unit.
If the vehicle has detected an emission-related
fault, the status is set to "faulty". It is then no
longer possible to pass the exhaust emission
test. In such cases the malfunction indicator
light is permanently lit to show the driver that
the vehicle should be taken to a workshop.